Following the events that disassembled the Avengers, Wanda Maximoff Scarlet Witch was left in the charge of Magneto and Professor Charles Xavier, both of whom were trying to rebuild the mutant nation of Genosha at the time. Enlisting the aid of Doctor Strange, Professor Xavier tried to cure Wanda of her insanity. Unfortunately, things appeared to be getting out of hand, and the combined efforts of Doctor Strange and Professor Xavier were not enough to help her.

Calling together the Avengers and the X-Men, Xavier and Strange held a group meeting to determine the fate of Wanda Maximoff. Quicksilver, who was eavesdropping, feared that the inevitable choice would be to kill her. Fearing for his sister, he hurried to Genosha where he pleaded to his father to protect Wanda. Magneto was torn-- he was unsure what the right choice was. His decision seemed to have been made.

When the Avengers and the X-Men flew to Genosha to check in on Wanda, Professor Xavier disappeared and suddenly the world burned white, to be replaced by a mutant utopia where humans had become the minority ruled under the House of M. No one remembered the world as it had been, except for S.H.I.E.L.D. agent Wolverine and a girl named Layla Miller, who exhibited the ability to unlock people's subconsciousnesses, reminding them of the world as it had been.

Uniting a group of heroes consisting primarily of the X-Men and the Avengers, those who remembered stormed the House of Magnus during a gala uniting all of the world's leaders, believing Magneto to be responsible for the world altering events. There, Doctor Strange discovered that it was not Magneto but Quicksilver who had manipulated Wanda into altering reality. Layla accidentally revealed to Magneto the world before the House of M. Enraged that Quicksilver had done such an atrocity in his name, Magneto killed his son. Wanda, who saw her brother's death, was traumatized. She quickly revived him from death and screamed to her father that he was a bad man, that mutants were freaks and that she hated him. As she seemed to calm down, Wanda said "No more mutants." Suddenly, the world burned white again...
...and the world returned as it had been, with only a few remembering the events of the House of M. As the world restored to normalcy, however, it became apparent that the majority of the world's mutants had lost their powers, Magneto and Quicksilver amongst them. With the bulk of the world's population ignorant of the world of the House of M, the shock of millions of mutants suddenly bereft of their genetic gifts caused widespread panic and the eventual quarantine of many mutants on to the grounds of the X-Mansion in Westchester.